Fabric conditioning for improved softening and antistatic properties is normally achieved by any of general methods including, for example, the addition of a fabric softening agent to the rinse cycle of a normal wash routine; the use of a substrate impregnated with a fabric conditioner composition for use in the dryer where the fabric conditioning agent is transferred to the clothes in the dryer; and the inclusion of the fabric softening agent with a detergent formulation for the wash cycle.
Commercial fabric conditioner formulations are most commonly based on quaternary ammonium salts. Formulations for use in the final clear water rinse, and dryer and detergent softeners, are normally based on difatty dimethyl quaternary salts, for example, dihydrogenated tallow dimethyl ammonium chloride (Adogen 442, Sherex Chemical Co., Inc.) or diamidoamine quaternary (Varisoft 222 Sherex Chemical Co., Inc.) or imidazoline based quaternaries.
Within recent years, there has developed a need for fabric softening compositions with faster biodegradation. Quaternary compounds with long chain alkenyl groups interrupted by ester groups are known, from e.g., French Patent 1,593,921. Softening compositions containing such materials are disclosed in European Patent No. 0 040 562.
U.S. Pat. No. 4,767,547 claims to attain rapid biodegradation by the inclusion of ester groups in long chain substituents of quaternary ammonium compounds. Similarly, U.S. Pat. No. 4,339,391 discloses esters based on hydroxyalkyl ammonium quaternary salts. U.S. Pat. No. 3,167,554 describes the reaction of a piperazine with polybasic acids to form polyamides with specific reference to the reaction between polybasic acids and hydroxyethyl piperazine wherein the amide formation is carried out under conditions which inhibit esterification of the hydroxy group.
U.S. Pat. Nos. 4,068,069 and 3,980,643 disclosed the preparation of esters of hydroxy alkyl piperazine using conditions which cause only esterification with no amide formation.
The present invention provides compositions containing quaternary ammonium salts which rapidly biodegrade, but are sufficiently shelf stable for commercial utility. The invention further provides quaternary salts having satisfactory softening properties for rinse cycle, dryer cycle, or wash cycle use while displaying acceptable biodegration coupled with sufficient shelf stability.